The present invention relates to a processing method and an apparatus therefor.
In a conventional processing apparatus, the object to be processed, such as a semiconductor wafer, is housed within a processing chamber and the processing apparatus is used to implement various processes by applying a processing gas uniformly to the semiconductor wafer while it is rotating within the processing chamber.
A predetermined liquid which is, for example, a mixture of hydrofluoric acid and water at either normal pressure or a positive pressure is accumulated in an upper part of the processing apparatus which is, for example, a natural oxide film removal apparatus that removes natural oxides formed on the surfaces of the semiconductor wafer, and a hydrofluoric acid vapor generated therefrom is diffused within the processing chamber. It is well known in the art to support the semiconductor wafer horizontally with the surface thereof that is be processed upward, on a mounting stand of a rotatable circular form in a lower portion of the interior of the processing chamber. The semiconductor wafer is rotated by rotating the mounting stand, and also the hydrofluoric acid vapor is applied to the surface of the semiconductor wafer in accordance with the rotational fluid flows created by the rotation of the mounting stand, and thus the natural oxide film formed on the surface of the semiconductor wafer is removed by the processing of this apparatus.
However, this method has a disadvantage in that, although the object to be processed is held by a holder mechanism that is provided on a rotatable mounting stand and is rotationally processed while in an atmosphere of a processing gas, the front and rear surfaces cannot be inverted during the processing of the natural oxide film or oxide film formed on the upper surface of the object to be processed, and thus it is impossible to uniformly remove the natural oxide film or oxide film formed on the rear surface of the object to be processed.
In addition, since it is not possible to uniformly remove the natural oxide film formed on the rear surface of the object to be processed, the coefficient of thermal expansion of the object to be processed and the coefficient of thermal expansion of the natural oxide film portion will be different when the object to be processed is passed to an apparatus that performs a subsequent process, such as a thermal processing apparatus that is a film-formation apparatus, and thus thermal stresses will be generated by the unevenness in thermal expansion between the central and peripheral portions of the object to be processed, which will reduce the yield.
When heavy metal contamination of the object to be processed is detected, an acidic solution is supplied to the upper surface of the object to be processed, the heavy metal deposited on the object to be processed is dissolved and removed thereby, or washed away. However, since it is not possible to rotate the front and rear surfaces of the object to be processed, the object to be processed is temporarily conveyed out of the processing apparatus after the front surface of the object to be processed is processed, its rear surface is inverted to become the upper surface, and the object to be processed is conveyed back into the processing apparatus. Thus, during this inversion, if heavy metal is deposited anew on the object to be processed while it is being inverted, there is the problem that the heavy metal contamination of the front and rear surfaces of the object to be processed cannot be analyzed under the same conditions.